Traumatic brain injury (TBI) is caused by a physical impact or other trauma that damages the brain. Depending on the source of the trauma, the resulting impact can cause an open head or a closed head injury. Open head injuries are typically caused by penetrating objects (e.g., a bullet or other projectile). Closed head injuries are often caused by blunt force trauma, such as the head hitting a windshield during a car accident. In both open and closed head injuries, there is immediate, primary damage to the brain (such as brain bleeding), followed by secondary brain damage (such as increased pressure within the skull and seizures) that evolves over time. Secondary brain damage sometimes affects the hippocampus region of the brain, which is involved in learning and memory. Secondary brain damage after a TBI can also affect cognitive, behavior and sensorimotor function to varying degrees.
Treatments for TBI vary based on the type and the severity of the injury. Surgery is sometimes needed to address primary brain damage and to stabilize a patient's condition. Acute treatment can sometimes be offered to minimize secondary damage, but such treatments tend to be palliative. For example, a patient may be administered sedating medications to induce a coma that will reduce the patient's agitation and facilitate healing. Medications to reduce spasticity may also be used as the patient recovers function. Other drugs may be used to assist with attention and concentration problems (including, for example, amantadine, methylphenidate, bromocriptine and antidepressants) or to subdue aggressive behavior (including, for example, carbamamazapine and amitriptyline). However, there are few effective drugs that directly treat or protect the brain from secondary brain damage.
Given the widespread incidence and lack of effective treatment options, there remains a significant unmet medical need to identify new methods for treating or preventing brain damage (e.g., secondary brain damage) caused by TBI.